Class: Just

Inherits:
Object
  • Object
show all
Includes:
Contracts::Core, Maybe
Defined in:
lib/maybe.rb

Overview

Just is a member of the Maybe union type that represents a non-null value. It’s used in conjunction with the Nothing type to allow one to gracefully handle null values without having to create a large amount of conditional logic.

Instance Method Summary collapse

Methods included from Maybe

Just, Nothing, #Proc, from_nullable, lift, of, zip

Constructor Details

#initialize(value) ⇒ Just

Returns a new instance of Just.


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# File 'lib/maybe.rb', line 329

def initialize(value)
  @value = value
end

Instance Method Details

#==(m) ⇒ Object 


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# File 'lib/maybe.rb', line 444

def ==(m)
  m.is_a?(Just) && m.get == get
end

#ap(m) ⇒ Object Also known as: apply 


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# File 'lib/maybe.rb', line 427

def ap(m)
  m.flat_map {|f| map(&f) }
end

#flat_map(&f) ⇒ Object 


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# File 'lib/maybe.rb', line 414

def flat_map(&f)
  f.call(@value)
end

#get ⇒ Object 


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# File 'lib/maybe.rb', line 343

def get
  @value
end

#get_or_else(&f) ⇒ Object 


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# File 'lib/maybe.rb', line 357

def get_or_else(&f)
  @value
end

#inspect ⇒ Object 


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# File 'lib/maybe.rb', line 456

def inspect
  "Just(#{@value.inspect})"
end

#just? ⇒ Boolean

Returns:

  • (Boolean) 

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# File 'lib/maybe.rb', line 365

def just?
  true
end

#map(&f) ⇒ Object 


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# File 'lib/maybe.rb', line 391

def map(&f)
  flat_map {|value| Maybe.of(f.call(value)) }
end

#nothing? ⇒ Boolean

Returns:

  • (Boolean) 

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# File 'lib/maybe.rb', line 373

def nothing?
  false
end